Currently, coaxial cables that are electrically and mechanically connected to coaxial connector plugs with solder require a labor intensive method of assembly that has many limitations. One such limitation is that many of the steps must be performed by hand. Hand assembly increases the cost of manufacture and poses risk of injury to the laborer occasioned by the use of sharp cutting blades and hot soldering irons. Moreover, handling of the cable during the assembly process results in additional injuries as the cable filaments tend to prick the fingers and hands of the laborer.
In the hand assembly of soldered coaxial connector plugs, the cable is first cut a predetermined length. Next, a portion of the cable's outer jacket is stripped from each end to expose the braided inner cable underneath. The braided inner cable is then debraided by machine and twisted. A portion of the insulation surrounding the inner cable is then stripped to expose the inner cable for electrical connection. The stripped inner cable is twisted and inserted through an opening at the tip of the center conductor, or pin, of the coaxial connector plug. A conductor is placed on the portion of the cable extending out of the connector plug opening, which opening is then dipped into solder, cleaned, and filed. Next, the twisted portion of the cable extending through the opening is soldered to the shell with a soldering iron and trimmed with a cable cutter. Finally, the assembled connector plug is ready for a plug molding to cover the outer shell of the connector.
A solution to the problems of manual soldering of coaxial connector plugs to a coaxial cable has been to crimp the connector to the cable. Most forms of crimping use a process of crimping the very tip of the center conductor pin. For some methods this may be the only crimp that is performed. A prong embedded through the outer insulative jacket to the outer braid conductor provides mechanical and electrical contact to the outer braid conductor. Problems associated with crimping the tip include that, upon insertion, the center cable can bend or be misguided so when the crimp occurs, no mechanical or electrical connection is achieved. Moreover, stray cables in a filament-type center conductor may fold back and cause electrical shorting if there is inadequate insulation between the outer and inner conductor shells of the connector plug. Finally, the crimp force of a single point crimp may deform the center conductor pin causing the center conductor pin to be mis-shapened so it cannot be properly inserted into the receptor portion of the coaxial connection assembly.
An improvement over the above-described methods is found in U.S. Pat. No. 5,207,596 which has been assigned to the assignee of the present invention. In that patent, a solderless coaxial cable connector and method for attachment is disclosed. The coaxial connector disclosed uses a closed-end coaxial plug whose electrical connection is made via double crimps made in at least three spaced apart positions about the circumference of the neck of the plug and the cable receptor portion. This connector poses problems, however, because the areas of double crimping are subject to failure due to fatigue. In addition, extra insulation is required between the outer surface of the plug and the coaxial cable to prevent shorting of the electrical connection between the cable and the connector housing, which extra insulation increases the overall cost of manufacturing the plug.
Accordingly, what is needed is an improved coaxial connector plug and method of assembly that avoids the above problems. In addition, the method should be automated to reduce the high cost of manual labor and to improve the yield rate of commercial product.